Microswitch structure



y 5, 1959 R. CARMICHAEL EIAL 2,885,517 MICROSWITCH STRUCTURE Filed Sept. 6, 1955 :QQQ

FA Q

INVENTORS ROBERT CARMICHAEL LOWELL G. COON W- 5% A ORA/[Y MICROSWITCH STRUCTURE Robert Carmichael, Lakewood, and Lowell G. Coon,

Westlake, Ohio, assignors to Union Carbide Corporation, a corporation of New York Application September 6, 1955, Serial No. 532,570

6 Claims. (Cl. 200--168) This invention relates to an improved mount for electrical switches, and more particularly concerns a microswitch holder in which connection to the microswitch terminals automatically results from the insertion of the microswitch into the holder, without requiring the disconnecting of any circuit wiring, and accurate positioning of the microswitch is effected.

It has heretofore been a well known practice in making a' switch repair or replacement to shut off the electric current and to disconnect the switch from the circuit wires. In many instances, where much use is made of switch units, it becomes necessary to inspect, repair and replace them at regular intervals. This procedure is costly and'time consuming if carried out by any of the known techniques. It has been proposed that instead of directly connecting the switch to an electrical line, a socket element or switch holder provided with terminal contacts be permanently connected to the line. The switch can then be inserted into the holder so that the contacts carried by the switch engage the contacts in the switch holder, and thus complete the circuit without dis connecting any line wiring.

However, in a switch holder for a microswitch there is a problem of providing a suitable receptacle in which a microswitch can be manipulated into operative adjustment in a minimum length of time. Principal features that are desirable in a switch housing for a microswitch are accurate positioning of the microswitch in the housing and quick-change means for removing and replacing the microswitch without disturbing any wire terminal connections.

It is, therefore, an important object of the present invention to provide a switch receiving structure having improved quick change means for installing and replacing a switch therein without requiring the disconnecting of line wires or the use of tools.

Another object of the present invention is to provide a microswitch receiving structure having not only improved means for installing and replacing a switch therein without requiring the disconnecting of line wires or the use of tools, but also improved flexibly resilient means for retaining and positioning the microswitch inside the switch structure.

In the drawings:

Fig. l is a sectional elevational view of a microswitch receiving assembly taken along the line 11 in Fig. 3;

Fig. 2 is a sectional view of the apparatus of the invention taken along the line 2-2 in Fig. 1; and

Fig. 3 is a sectional view taken along the line 33 in Fig. 1.

A switch structure 1! embodying features of the present invention is adapted to receive a conventional microswitch assembly 11 of either the double throw type, the single throw-normally closed type, or the single thrownormaily open type.

Thernicroswitch assembly 11 comprises a switch case 13 made of a suitable electrical insulating material having secured to one end of its base a switch terminal 14 l i United States Patent 0 and at the other end a pair of switch terminals 16 and 17, said terminals being of approximately the same length and width. The terminal 14 is located between a pair of flat surface projections 18, 18, integral with the switch casing 13, and the terminals 16 and 17 lie between spaced, rib-like projections 19, 20, and 21 in said casing.

Directed generally upwardly and longitudinally from the upper surface of the microswitch casing 13 is a conventional spring loaded lever arm 22, which is pivotally secured at one end to the microswitch casing at 23. Attached to the other end of the lever 22 is a roller assembly 25 to adapt the microswitch to use with. moving cams and slides.

The switch structure 10 of the invention comprises a hollow insulating body or switch holder 26 which may be precision molded from a shape retaining thermosetting plastic material, preferably a phenolic resin having high chemical and impact resistances and good electrical insulating qualities. The insulating body 26 is comprised of a base 27 provided with side walls 28, 29, terminating in anupper wall 30. Access of the microswitch 11 into the interior of the switch holder 26 is affored by an opening 32 at one end of the body 26. In the upper wall 30 there is provided an open ended slot 33 through which the roller assembly 25 may reciprocatingly move. An end wall 34 in said body limits the longitudinal travel of the microswitch, and, together with the side walls 28, 29 and the upper wall 30, defines the operative position in which the microswitch may nest.

According to the invention, means are provided for automatically connecting and disconnecting the microswitch terminals from an electrical circuit during the application and removal of the microswitch from the switch receptacle. For this purpose, contact with the terminal 14 and the individual terminals 16 and 17 of the microswitch 11 is consummated by unitary, flexibly resilient, leaf spring contact elements or spring clips 36 and 37 carried by the base wall 27. Preferably, these contact elements are molded as an integral part of the holder 26. These leaf spring elements may be made from a thin gauge, electrically conductive, spring-type material such as brass, silver, Phosphor bronze, or beryllium copper. The contact element 36 has an elongated inner portion or flexible tab 38 and the contact element 37 is provided with split tabs 3% and 3917, said tabs extending at a slight incline to the base wall 27 into the interior of the insulating body 26 and being angled in the direction of the respective switch terminals 14 and 16, 17 to effect contact therewith. As shown in Figs. 2 and 3, the flexible tabs 39a, 39b, for the common contact element 37 are spaced to contact respectively the switch terminal 16, 17. Depending on whether the microswitch is of the normally open or normally closed type, one or the other of the switch terminals 16, 17 will be electrically joined to the contact element 37.

In the switch structure of the present invention means are provided for avoiding transverse displacement of the flexible tabs, 38 and 39a, 39b, of the contact elements, 36 and 37, relative to the microswitch since such movement tends to throw said tabs out of registry with their respective microswitch terminals 14 and 16, 17. To this end, each of these tabs 38, 39a, 3% which are provided with downturned terminals 40, is constructed with the same width which is slightly less than the spacing between either the projections 18, 18, the projections 19, 2% or the projections 20, 21, so that in assembling the switch structure each of the tabs may slidingly move between a pair of switch terminal projections. With the aforesaid construction, there is little likelihood of any member catching on the contact element and deranging same when removing or inserting the microswitch.

Integral with each of the contacting elements 36, 37

3 ris a flat end section 41, 42 extending outside the switch receptacle and angularly bent to lie flat against the external surface of the base 27. Securernent of electrical power leads 43, 44 to the bent sections 41, 42, is accomplished by self-tapping screws 45, 46 which are adapted to screw into drilled holes 47, 48 provided for this purpose in the base wall 27.

It is to be pointed out at this stage that the tabs, 39a and 391; which are in engagement with the microswitch terminals 16 and 17, have a common contacting element 37 which in turn makes contact with the electrical lead 44. The remaining terminal 14 of the microswitch 11 makes direct electrical contact with the contact element 38 which is connected to the electrical lead 43. The flexible resiliency of the tabs 38 and 39a, 39b, provides suflicient bias to insure a continuous electrical path.

The entire switch structure may be supported within the confines of a machine, on a wall or mounting bracket 49 next to a machine or in a switching center or other desired place. For this purpose the switch structure may be detachably attached to the wall 49 by threaded bolts 50, 51, each having an unthreaded shank portion 52, 53, passing through a drilled aperture 54, 55, provided therefor in the base wall 27. Any number of bolts may be used to secure the switch structure in place, two being shown and illustrated in the drawings. 1

In utilizing the switch structure of the invention for wide varieties of industrial and laboratory uses, particularly where heavy vibrations are encountered, the magnitude of vibration may be greater than the microswitch structure may be equipped to handle, without incurring serious injury to the basic switch mechanism. T o avoid this contingency and to protect the basic switch from dangerous overloading movements which may be applied to the microswitch roller assembly 25, provision is made in the present invention for supplementary overtravel of the microswitch 11 in the insulating body 26. Accordingly, the inner surface of the base wall 27 is provided with recesses 56, 57 which are so constructed and arranged to receive therein the flexible tabs 38 and 39a, 3%, when overtravel or excessive movement of the microswitch is encountered. In the extreme depressed position, the tabs 38, 39a and 3% will lie approximately flush with the inner surface of the base wall 27.

In accordance with the invention, the flexibly resilient spring clps 36, 37 are utilized in cooperation with the microswitch 11 not only as a means for effecting contact with the microswitch terminals, but also as a means for urging and retaining the microswitch in operative posi tion. Accordingly, when the microswitch 11 is applied by generally centering it with respect to the opening 32 in the switch holder 26 and then pushing longitudinally inwardly, the flexibly resilient tab 38 will engage the rib 20 of the microswitch and begin camming downwardly into the clearance space afforded by the depression 56 until the rib 2t enters the space between the split tabs 39a and 3%. At this point the rib 20 will have traversed the flexible tab 38. Final positioning of the microswitch 11 is then accomplished by pushing it the full length of the switch receptacle 26 to the assembly position shown in Fig. l. Thereby, the flexible tabs 38 and 39a, 3% make automatic connection with the microswitch terminals 14 and 16, 17, without the necessity of stripping any wires or using any tools, and the flexible tabs are flexibly tensioned by the downward deflection thereof, reacting to thrust the microswitch into operative position in firm switch retaining engagement with the switch holder walls 30 and 34.

As a feature of the present invention provision is made in the switch structure for facilitating removal of the microswitch 11 from the switch holder 26. Accordingly, the end wall 34 is provided with a slotted opening or window 58 large enough to permit the insertion therethrough of the finger of an operator. Thus, in removing the microswitch, it may be held by the thumb and index 4 finger of one hand at the projecting end of the microswitch, and retraction of the microswitch may be initiated by lightly pushing the index finger of the other hand through the window 58.

One of the most important advantages of the present invention is that the replacement of a defective microswitch may be quickly performed, particularly in the situation where the defective switch is in a set of switches and it is not known which one in the set is defective. All the microswitches in the set may be quickly removed and replaced with a new set of microswitches, thereby considerably shortening the period of the shut-down and lengthening the period of productivity.

It will be understood that modifications and variations may be effected without departing from the novel concepts and scope of the invention.

What is claimed is:

1. In a microswitch structure including a microswitch having multiple switch terminals and a projecting switch actuating member, a switch receptacle for the microswitch comprising a hollow insulating body having an opening at one end and an end wall at the other end thereof for abuttingly receiving the microswitch in a predetermined operative position, a slot in said body for the movement therethrough of the switch actuating member during the application and removal of the microswitch, a plurality of contact elements carried by said body, each of said contact elements having one end portion extending into the interior of said body and in respective engagement with the switch terminals and the opposite end portion extending outside said body, said contact elements cooperating with said end wall to accurately position and immovably retain said microswitch in said operative position, and a plurality of electrical power leads secured to the outside of said body and connected respectively to said contact elements, whereby connection of the power leads to the switch terminals automatically results from the insertion of the microswitch into the operative position in said switch receptacle and said microswitch is automatically disconnected when moved out of said operative position;

2. In a microswitch structure including a microswitch having multiple switch terminals and a projecting switch actuating member, a switch receptacle for the microswitch comprising a hollow insulating body having an opening at one end for receiving the microswitch, a slot in said body for the movement of the switch actuating member during the application and removal of the microswitch, a plurality of contact elements carried by said body, each of said contact elements having one end portion extending into the interior of said body and in respective engagement with the switch terminals and the opposite end portion extending outside said body, and a plurality of electrical power leads secured to the outside of said body and connected respectively to said con tact elements, said interior portions of said contact elements being leaf springs to urge and immovably retain said microswitch into predetermined engagement with said receptacle body, whereby operative connection to the switch terminals automatically results from the insertion of the microswitch into the operative position in said switch receptacle.

3. In a microswitch structure including a microswitch having multiple switch terminals and a projecting switch actuating member, a switch receptacle for the microswitch comprising a hollow insulating body having an opening at one end and an end wall at the other end for abuttingly receiving the microswitch, a slot in said body for the movement of the switch actuating member during the application and removal of the microswitch, a plurality of contact elements carried by said body, each of said contact elements having one end portion extending into the interior of said body and in respective engagement with the switch terminals and the opposite end portion extending outside said body, a plurality of electrical power leads secured to the outside of said body assume 5 and connected respectively to said contact elements, whereby connection to the switch terminals automatically results from the insertion of the microswitch into the switch receptacle and the abutment of said microswitch against said end wall, and means for mounting said body on a wall panel.

4. In a microswitch structure including a microswitch having multiple switch terminals and a projecting switch actuating member, a switch receptacle for the microswitch comprising a hollow insulating body having an opening at one end for receiving the microswitch, and an opening at the other end of said body for facilitating removal of the microswitch, a slot in said body for the movement of the switch actuating member during the application and removal of the microswitch, a plurality of contact elements carried by said body, each of said contact elements having one end portion extending into the interior of said body and in respective engagement with the switch terminals and the opposite end portion exten ing outside said body, a plurality of electrical power leads secured to the outside of said body and connected respectively to said contact elements, whereby connection to the switch terminals automatically results from the insertion of the microswitch into the switch receptacle and the abutment of said microswitch against said other end of said body.

5. In a microswitch structure including a microswitch having multiple switch terminals and a projecting switch actuating member, a switch receptacle for the microswitch comprising a hollow insulating body having an opening at one end for receiving the microswitch and an abutment for positioning said microswitch into operative assembly, a slot in said body for the movement of the switch actuating member during the application and removal of the microswitch, a plurality of contact elements carried by said body, each of said contact elements having one end portion extending into the interior of said body and in respective engagement with the switch terminals and the opposite end portion extending outside said body, said interior portions of said contact elements being leaf springs to urge and maintain said microswitch in predetermined engagement with said receptacle body, a plurality of recesses in the interior of said insulating body in cooperative association respectively with said leaf springs, a plurality of electrical power leads secured to the outside of said body and connected respectively to said contact elements, whereby connection to the switch terminals automatically results from the insertion of the microswitch into the switch receptacle and in firm engagement with said abutment, and said springs and recessions otter protection to the microswitch when overtravelling forces are applied to the switch actuating member.

6. In combination with a microswitch having multiple switch terminals and a projecting switch actuating member, a microswitch holder for receiving said microswitch, said microswitch holder having multiple contact elements adapted to register respectively with said switch terminals, an opening in said holder for ready insertion and removal of said microswitch, said opening having a slotted portion for the projection therethrough of said switch actuating member, a terminal wall in said slotted opening coacting with said contact elements for positioning said microswitch into operative position, said holder being adapted to accommodate and immovably hold said microswitch in fixed position, whereby said switch may be actuated by a predetermined mechanical force solely in said operative position.

References Cited in the file of this patent UNITED STATES PATENTS 2,076,558 Hartman et al. Apr. 13, 1937 2,281,808 Smiley May 5, 1942 2,284,644 Dubilier June 2, 1942 2,368,679 Popp Feb. 6, 1945 2,531,350 Chrastina Nov. 21, 1950 2,542,651 Franklin et a1. Feb. 20, 1951 2,734,115 Dupre Feb. 7, 1956 

